Automatic slack-adjuster.



R. G. SWARTZWELDER. AUTOMATIC SLACK ADJUSTER.

APPLIGAIION FILED AUG.5, 1911.

1,122,436. Patented Dec.29,1914.

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WITNESSES OR UNITED STATES PATENT OFFICE.

RICHARD C. SWARTZWELDER, OF EDGEW'QOD, PENNSYLVANIA, ASSIGNOR TO THEWESTINGHOUSE AIR BRA-IKE COMPANY, OF PITTSBURGH, PENNSYLVANIA, A GQRPO-RATION OF PENNSYLVANIA.

Specification of Letters Patent.

Patented romeo, 1 914..

Application filed August 5, 1911. Serial N 0. 642,534.

To all whom it may concern: I

Be it known that I, RICHARD C. SWARTZ- WELDER, a citizen of the UnitedStates, residing at Edgewood, in the county of Allegheny and State ofPennsylvania, have invented new and useful Improvements in AutomaticSlack-Adjusters, of which the following is a specification.

This invention relates to fluid pressure brakes, and more particularlyto a slack adjuster for automatically taking up slack when the brakepiston travel exceeds a predetermined amount.

The principal object of my invention is to provide an improvedpneumatically operated slack adjuster, positive in operation, and ofsimple, compact construction.

In the accompanying drawing; Figure 1 is a central sectional view of aslack adjuster embodying my improvement, with the parts in normalposition; Fig. 2 a similar view, showing the parts in the positionassumed upon applying the brakes when the brake piston travel exceeds apredetermined amount; and Fig. 3 a plan view of the slack adjusterapplied to a brake cylinder.

As shown in Fig. 3 of the drawing, the slack adjuster 1 may be appliedto take up the slack by adjustment of the rear fulcrum block in theusual well known manner or otherwise, and said slack adjuster may becontrolled by fluid supplied from the brake cylinder 2 through pipe 3when the brake cylinder piston travel exceeds a predetermined amount.

My improvement may be applied to any form of slack adjuster in whichmovement is required to take up the slack, and to illustrate the use ofsame the invention is shown applied to a well known commercial type ofslack adjusterfin which a ratchet wheel 4 is adapted upon rotation by apawl 5 to cause longitudinal movement of a screw, which movement causesthe slack to be taken up. As this form of slack adjuster is clearlydescribed in prior Patent No. 696,521 of H. A. Vahlert, dated April 1,1902, it will be unnecessary to further describe or illustrate the samein the present application. According to my invention, a piston devicehaving difl'erential piston heads 6 and 7 is provided for operating saidpawl, the pawl being pivotally connected to a stem 8 carried by thepiston device.

The chamber 9 intermediate the piston heads 6 and 7 contains a movablesleeve 10 loosely inclosing the piston rod 11 and carrying a projectingstem 12 adapted to operate a slide valve 13 contained in a. valvechamber 14. The sleeve 10 is of such length that the extreme movement ofthe piston device in one direction is adapted to move the sleeve one waywhile the extreme movement of the piston device in the oppositedirection is adapted to shift the sleeve the opposite way. The valvechamber 14 is connected by a'passage 15 with a reservoir 16 which isnormally charged with fluid under pressure supplied through pipe 17either from the train pipe or other suitable source of fluid pressure. 7a In operation, assuming the parts in the position shown in Fig. 1, thechamber 9 intermediate the piston heads 6 and 7 is connected through acavity 19 in the valve 13 with an exhaust port 20, so that all sides ofthe piston device are normally at atmospheric pressure. Upon applyingthe brakes, if the brake piston travel exceeds the predetermined degree,air from the brake cylinder is admitted through pipe 3 to chamber 18 ofthe piston head 7. The piston device thereupon shifts the pawl 5 to theposition shown in Fig. 2. In this position, the exhaust port 20 is cutoff from chamber 9 and a port 21 connects valve chamber 14 with chamber9, so that fluid under pressure is admitted from the reservoir 16 to thechamber 9. So long as the brakes are applied this pressure will have noeffect, as the brake cylinder pressure acting on the full area of piston7 exceeds the pressure acting on the differential areas of the pistons 6and 7 in the chamber 9. Upon releasing the brakes, however, the brakecylinder pressure on piston head 7 in chamber 18 is also released andconsequently the pressure in chamber 9 is suflicient to shift the pistondevice to the position shown in Fig. 1, and thereby rotate the ratchetWheel 4 through the action of the pawl 5 to take up the slack. Beforethe piston device reaches its extreme position the piston head 6 engagesthe sleeve 10 and shifts the valve 13 so as to cut off the supply port21 and connect chamber 9 to the exhaust port 20.

It Will now be apparent that a simple construction is provided wherebythe slack may be positively taken up by the direct action of fluid underpressure.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is

1. A slack adjuster for fluid pressure brakes comprising means fortaking up the slack, a valve, and a piston device operated upon anapplication of the brakes for actuatingsaid valve to supply fluid tosaid piston device.

2. A slack adjuster for fluid pressure brakes comprising means fortaking up the slack, a valve, and a piston device, operated in onedirection by fluid under pressure upon applying the brakes, foractuating said valve to supply fluid under pressure to said pistondevice tending to move said piston device in the opposite direction.

3. The combination with a brake cylinder, of a slack adjuster comprisingmeans for taking up the slack, a piston device for actuating said means,said piston device being operated in one direction by fluid from thebrake cylinder when the brake piston travel exceeds a predeterminedamount, and a valve operated by said piston device for supplying fluidto same to eflect the movement thereof in the opposite direction uponrelease of fluid at brake cylinder pressure therefrom.

4%. A slack adjuster for fluid pressure brakes comprising means fortaking up the slack, a differential piston device operated in onedirection by fluid from the brake cylinder for actuating said means, anda valve operated by said piston device for supplying fluid to move saidpiston device in the op posite direction.

5. A slack adjuster for fluid pressure brakes comprising means fortaking up the slack, a differential piston device subject on one side tofluid from the brake cylinder for actuating said means, a reservoirnormally charged with fluid under pressure, and a valve operated by saidpiston device for supplying fluid from said reservoir to thedifferential area of the piston device to thereby shift same uponrelease of fluid at brake cylinder pressure therefrom.

In testimony whereof I have hereunto set my hand.

' RICHARD G- SWARTZWELDER.

Witnesses: v

A. M. CLEMENTS, G. A. ALLsHoUsn.

Copies of this patent may he obtained for five cents each, by addressingthe Commissioner of Eatents, Washington, D. 0.

